Oxygenator

ABSTRACT

An oxygenator apparatus for use in an extracorporeal circuit. The apparatus includes a housing and a membrane assembly disposed within the housing. The membrane assembly includes a first plurality of gas exchange elements disposed in a first zone and a second plurality of gas exchange elements disposed in a second zone. The second zone is arranged concentrically around the first zone. The first and second plurality of gas exchange elements are fluidly open along a body and fluidly separated along a distal end. The first zone is configured to be fluidly coupled to an oxygen source and the second zone is configured to be fluidly coupled to a negative pressure source. A blood flow path includes a generally radial flow through the first zone to add oxygen to the blood and the second zone to separate gaseous micro emboli from the blood through the plurality of gas exchange elements.

CROSS-REFERENCE TO RELATED APPLICATIONS

This Patent Application is a Continuation of U.S. patent applicationSer. No. 16/170,390, entitled OXYGENATOR, filed Oct. 25, 2018 of whichis incorporated herein by reference.

FIELD

The present technology is generally related to oxygenating blood in anextracorporeal blood circuit. More particularly, the present disclosurerelates to systems and methods for optimizing removal of gaseous microemboli from a patient's blood through an oxygenator operating in anextracorporeal blood circuit.

BACKGROUND

An extracorporeal blood circuit is commonly used during cardiopulmonarybypass to withdraw blood from the venous portion of the patient'scirculation system (via a venous cannula) and return the blood to thearterial portion (via an arterial cannula). The extracorporeal bloodcircuit typically includes a venous drainage line, a venous bloodreservoir, a blood pump, an oxygenator, a heat exchanger, one or morefilters, and blood transporting tubing, ports, and connection piecesinterconnecting the components.

Blood oxygenators are disposable components of extracorporeal circuitsand are used to oxygenate blood. In general terms, the oxygenator takesover, either partially or completely, the normal gas exchange functionof the patient's lungs. The oxygenator conventionally employs amicroporous membrane or bundle comprised of thousands of microporous orsemipermeable hollow fibers. Blood flow is directed around the outsidesurfaces of the hollow fibers. Concurrently, an oxygen-rich gas mixtureis passed through the fiber lumens. The hollow fibers are considered toform a membrane, separating the “gas side” from the “blood side” pathwayof the oxygenator with the wall of the hollow fiber separating the gasside from the blood side. Due to the relatively high concentration ofcarbon dioxide in the blood arriving from the patient, carbon dioxide istransferred from the blood, diffusing across the microporous fibers andinto the passing stream of oxygenating gas. At the same time, oxygen istransferred from the oxygenating gas, diffusing across the fibers andinto the blood. The oxygen content of the blood is thereby raised, andthe carbon dioxide content is reduced.

Conventionally, a filter device (e.g., an arterial filter) is be fluidlyconnected within the extracorporeal circuit downstream from (or upstreamof) the oxygenator, and operates to remove gross air (e.g., air bubbles)and particles on the order of 18-45 microns, as well as trap gaseousmicro air or micro bubbles, sometimes referred to as gaseous microemboli(GME). Arterial blood filters can incorporate a membrane or screenfilter media with a sufficiently small porosity for capturing GME. Theoxygenator and arterial filter devices normally are physically separatedcomponents or devices of the circuit.

Maximizing removal of Gaseous Micro Emboli (GME) from the patient'sblood is considered beneficial by reducing potential harms resultingfrom delivery of emboli to the patient. Considerations for maximizingGME removal is limited by the physiological considerations required forgas transfer to the patient through the hollow fibers.

SUMMARY

Some aspects in accordance with principles of the present disclosurerelate to an oxygenator apparatus for use in an extracorporeal circuit.The apparatus includes a housing and a membrane assembly. The housinghas a blood inlet, a blood outlet, and a blood flow path from the bloodinlet to the blood outlet. The housing defines a central axis and aseries of zones concentrically disposed around the central axis. Themembrane assembly is disposed within the housing. The membrane assemblyincludes a first plurality of gas exchange elements disposed in a firstzone of the housing and a second plurality of gas exchange elementsdisposed in a second zone of the housing. The second zone is arrangedconcentrically around the first zone and the zones are fluidly open toone another along a body of the plurality of gas exchange elements andfluidly separated from one another along a distal end. Each of theplurality of gas exchange elements including an interior gas side and anexterior blood side. The first zone is configured to be fluidly coupledto an oxygen source to supply oxygen flow within the interior gas sideof the first plurality of gas exchange elements of the first zone andthe second zone is configured to be fluidly coupled to a negativepressure source to apply negative pressure to the interior side of thesecond plurality of gas exchange elements in the second zone. The bloodflow path includes a generally radial flow through the first zone andthe second zone, the first zone to add oxygen to the blood and removecarbon dioxide from the blood, and the second zone to separate gaseousmicro emboli from the blood through the plurality of gas exchangeelements.

Other aspects in accordance with principles of the present disclosurerelate to a method of oxygenating blood and removing gaseous microemboli within an extracorporeal blood circuit. The method includesdelivering blood from a patient to an oxygenator apparatus. Theoxygenator apparatus includes a housing and a membrane assembly disposedwithin the housing. The housing includes a blood inlet and a bloodoutlet. The housing defines a central axis and a series of zones fluidlyopen to one another and concentrically disposed around the central axis.The membrane assembly includes a plurality of gas exchange elementsforming a first zone arranged around the central axis and a second zonearranged around the first zone. Each of the plurality of gas exchangeelements includes an exterior surface and an interior lumen formed by aninterior surface. The interior lumens of the plurality of gas exchangeelements in the first zone are fluidly coupled to an oxygenation source.The interior lumens of the plurality of gas exchange elements in thesecond zone are fluidly coupled to a negative pressure source. Themethod includes directing blood from the blood inlet to the blood outletalong a blood flow path, oxygenating the blood and removing carbondioxide from the blood as the blood flows radially through and aroundthe plurality of gas exchange elements in the first zone, applying anegative pressure to an interior lumen of the plurality of gas exchangeelements in the second zone, filtering gaseous micro emboli from theblood into the interior of at least one of the second plurality ofelements, and removing the blood from the apparatus via the bloodoutlet.

Other aspects in accordance with principles of the present disclosurerelate to a system for treating blood in an extracorporeal circuit. Thesystem includes an oxygenator apparatus, an oxygen source, and anegative pressure source. The oxygenator apparatus includes a housinghaving a blood inlet and a blood outlet. The housing defining a centralaxis and a series of zones fluidly open to one another andconcentrically disposed around the central axis. The oxygenatorapparatus includes a core disposed along the central axis of thehousing, the core configured to receive blood from a patient through theblood inlet, a first zone including a first plurality of gas exchangeelements arranged around the core, and a second zone including a secondplurality of filter elements arranged around the first plurality of gasexchange elements. The oxygen source is fluidly coupled to the firstplurality of filter elements at the first zone to supply oxygen tointerior lumens of the first plurality of filter elements. The negativepressure source is fluidly coupled to the second plurality of filterelements at the second zone to provide suction to interior lumens of thesecond plurality of filter elements. The oxygenator apparatusestablishes a blood flow path from the blood inlet to the blood outlet,including generally radial flow to add oxygen to the blood and removecarbon dioxide from the blood at the first plurality of gas exchangeelements and separate gaseous micro emboli from the blood at the secondplurality of filter elements.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B are a schematic cross-sectional views of exampleoxygenator apparatuses in accordance with aspects of the presentdisclosure.

FIG. 2A a schematic cross-sectional view of another example oxygenatorapparatus in accordance with aspects of the present disclosure.

FIG. 2B a schematic cross-sectional view of the oxygenator apparatus ofFIG. 2A, viewed perpendicular to the cross-sectional view of FIG. 2A, inaccordance with aspects of the present disclosure.

FIG. 3 a schematic cross-sectional view of another oxygenator apparatusin accordance with aspects of the present disclosure.

FIG. 4 a schematic cross-sectional view of another oxygenator apparatusin accordance with aspects of the present disclosure.

FIGS. 5A and 5B are cross-sectional views of an oxygenator apparatus inaccordance with aspects of the present disclosure.

FIG. 6 is a schematic illustration of an extracorporeal circuitincluding an oxygenator apparatus of the pending disclosure.

DETAILED DESCRIPTION

An oxygenator apparatus 100 for use in an extracorporeal blood circuitin accordance with aspects of the present disclosure is illustrated inthe partially cross-sectional view of FIG. 1A. The oxygenator apparatus100 includes a housing 112 and a membrane assembly 114. The housing 112defines a central axis “C” and a series of zones fluidly open to oneanother and concentrically disposed around the central axis “C”. Themembrane assembly 114 is disposed within the housing 112. The membraneassembly 114 includes a plurality of gas exchange elements 120 disposedin and forming a first zone 122 and a second zone 124. The first andsecond zones 122, 124 of the membrane assembly 114 may be considered asdividing a volume within the housing 112. The first zone 122 is arrangedaround the central axis “C” and the second zone 124 is arranged aroundthe first zone 122, as discussed further below.

The membrane assembly 114 includes a first plurality or bundle of gasexchange elements 120 a forming the first zone 122 and a secondplurality or bundle of gas exchange elements 120 b forming the secondzone 124 within the housing 112. The first zone 122 can be anoxygenation zone and the second zone 124 can be a gaseous micro emboli(GME) removal zone, although both oxygenation can be supplied to, andGME removed from, either of both of the first and second zones 122, 124.The second, or gaseous micro emboli removal, zone 124 is arrangedconcentrically around the first, or oxygenation, zone 122. The firstzone 122 and the second zone 124 are fluidly open to one another along abody of the plurality of gas exchange elements 120 of the membraneassembly 114. The first and second plurality of gas exchange elements120 a, 120 b can extend co-axially along the central axis “C” of thehousing 112, extending from a first, proximal, end to an opposingsecond, distal, end of the housing 112 (not shown).

The bundle or plurality of hollow tube fiber gas exchange elements 120of the membrane assembly 114 are used for gas exchange and made ofsemi-permeable membranes including micropores. In some embodiments, thegas exchange elements 120 are hollow polypropylene fibers, but othermaterials are also acceptable. Any suitable microporous fiber can beused as the gas exchange elements 120 of the oxygenator. The gasexchange elements 120 can have an interior lumen formed by an interiorsurface of a fiber wall and an exterior surface (not shown). In someembodiments, the first and second plurality of gas exchange elements 120a, 120 b are formed of the same fibrous bodies. In some embodiments, thefirst plurality of gas exchange elements 120 a is a first type offibrous body, or membrane, and the second plurality of gas exchangeelements 120 b is a second type of fibrous body, or membrane.

The partial cross-sectional view of the oxygenator apparatus 100 of FIG.1A illustrates an example of how blood can flow through the oxygenatorapparatus 100. In general terms, a blood flow path (indicated by arrows“B”) is established from the blood inlet to the blood outlet (notshown). The blood flow path “B” may be generally longitudinally alongthe central axis “C” from the blood inlet and flow radial through achamber 138 of the oxygenator apparatus 100 including the first andsecond zones 122, 124. The first zone 122 is fluidly open to the secondzone 124 within the chamber 138, with the first zone 122 having anenlarged volume as compared to that of the second zone 124. Thecylindrical shape establishes the central axis “C” of the housing 112extending through the chamber 138. Blood flow path “B” flows around andpast the hollow fibers of the first plurality of gas exchange elements120 a in the first zone 122 and then of the second plurality of gasexchange elements 120 b in the second zone 124 to the blood outlet (notshown).

As the blood flow “B” moves through and around the first plurality ofgas exchange elements 120 a in the first zone 122, oxygen-containing gasmedium flows through the interior (gas) side of the gas exchangeelements 120 a, as indicated by arrows “0”, adding oxygen to andremoving carbon-dioxide from the blood. An oxygen-containing gas mediumis provided to flow through the interior (gas) side of the gas exchangeelements 120 to permeate the fibers of at least the first zone 122.Oxygen may diffuse through the hollow fibers into the blood while carbondioxide may diffuse into the hollow fibers and be removed, or separatedout of the blood. Carbon dioxide from the blood surrounding the fibersdiffuses through the walls of the fibers and into the gas mixture.Similarly, oxygen from the gas mixture inside the fibers diffusesthrough the micropores into the blood. The gas mixture then has anelevated carbon dioxide content and preferably exits the opposite endsof the fibers as it moves out of the apparatus via a gas outlet. Othergases may also be transferred in addition to the oxygen and carbondioxide exchanged. For example, an anesthetic gas can be included in theoxygen-containing gas medium to be infused into the blood.

The proximity of the blood and oxygen facilitates gas transfer throughmicropores in the fiber wall of the gas exchange elements 120 a viadifferences in partial pressures. The rate of gas transfer is dependentupon partial pressure differences between the gas side and the bloodside of the fiber membrane. Operating parameter inputs that impactpartial pressure differences are limited by gas transfer considerationsdriven by patient physiological demand. Some of the inputs include gassweep or flow rate through the fibers, and the percentage of pureoxygen/ambient air that is blended together and fed in the gas pathwayof the fibers. Other inputs can also impact partial pressuredifferences. After the blood has flowed around the fibers of the bundleof gas exchange elements 120 a, the blood is routed to a secondplurality of gas exchange fiber elements 120 b.

As the blood flow “B” continues to move radially through and around thesecond plurality of gas exchange elements 120 b in the second zone 124.Negative pressure is applied to the “gas” side of the plurality of gasexchange elements 120 b to pull GME from the blood into the “gas” sideof the plurality of gas exchange elements, as indicated by arrows “Gi”or “G2”, illustrated in FIGS. 1A and 1B, respectively. The secondplurality of gas exchange elements 120 b can be fluidly coupled to anegative pressure source at one of either the distal or proximal end ofthe second plurality of gas exchange elements 120 b forming the secondzone 124. Gas transfer including gaseous micro emboli can occur uponpartial pressure differences between the gas side and the blood side ofthe fiber membranes of the second plurality of gas exchange elements 120b, with the interior gas side having a lower pressure than the bloodside. The second plurality of gas exchange elements 120 b of the secondzone 124 can be provided an oxygen-contain gas medium, or can beprovided another source of gas medium, or open to atmosphere at the end(i.e., proximal or distal end) opposite of the negative pressure source.In some embodiments, the ends of the second plurality of gas exchangeelements 120 b in the second zone 124 opposite of the end the negativepressure source is applied to are fluidly closed. In one embodiment,negative pressure can be selectively applied to the one end of thesecond plurality of gas exchange elements 120 b of zone 124 independentof the gas flow, pressure and other inputs to the first plurality of gasexchange fibers to optimize GME removal from the blood without gasexchange consideration limitations of the first plurality 120 a becausethe first zone 122 is isolated, or essentially isolated, from thenegative pressure source.

The gas pathway zones indicated by arrows “0” and “G” for oxygen gastransfer “0” and GME removal “G”, respectively, can be separate andindependent from one another. The fluid flows (e.g., indicated by arrows“G” and “0”) through the apparatus 100 can be maintained separately andcompartmentalized to increase effectiveness and efficiency of bothoxygenation of the blood and removal of the GME from the blood in theoxygenator apparatus 100. After the blood has flowed around the fibersof the bundle of gas exchange elements 120 a and 120 b it is routedoutside the oxygenator housing 112 via a blood outlet port.

The membrane assembly 114 is disposed around the central axis “C”. Insome embodiments, the plurality of gas exchange elements 120 of theoxygenating first zone 122 can be wound onto or around a volumedisplacing core 136 or other centrally disposed body suitable forattachment and winding of the gas exchange elements. In someembodiments, the first and second plurality of gas exchange elements 120a, 120 b are disposed helically extending in a single direction. In someembodiments, the first plurality of gas exchange elements 120 a disposedhelically around the central axis “C” in a first direction and thesecond plurality of filter elements 120 b are disposed helically aroundthe first plurality of gas exchange elements 120 a in a second directionopposite the first direction. The plurality of gas exchange elements 120can be disposed in any suitable manner within and forming the first andsecond zones 122, 124.

The oxygenator apparatus 110 illustrated in FIG. 1B is similar to FIG.1A. In the embodiment of FIG. 1B, the blood flow “B” moves radiallythrough and around the first plurality of gas exchange elements 120 a inthe first zone 122 and the second plurality of gas exchange elements 120b in the second zone 124. As the blood flow “B” moves through and aroundthe plurality of gas exchange elements 120 a, an oxygen-containing gasmedium flows through the interior (gas) side of the gas exchangeelements 120 a, as indicated by arrows “0”, permeating the fibers of thegas exchange elements 120 a to add oxygen to and remove carbon-dioxidefrom the blood. After the oxygen-containing gas medium flows through andexits out of the ends of the first plurality of gas exchange elements120 a, the flow “T” transitions into the ends of and through the secondplurality of gas exchange elements 120 b, as pulled by a negativepressure source indicated by flow “G2”. The transition flow “T” may beopposite the initial flow “0”. In one embodiment, ventilation toatmosphere may be provided at the transition between the first pluralityof gas exchange elements 120 a in the first zone 122 and the secondplurality of gas exchange elements 120 b in the second zone 124 asindicated by arrows “A”. Ventilation to atmosphere can assist withmaintaining pressure and eliminating positive pressure build up in thefirst zone 122. The housing 112 includes inlets, outlets, andventilation ports as appropriate.

As illustrated in the example embodiments illustrated in FIGS. 2-5, theapparatuses of the present disclosure can combine various components ofextracorporeal blood circulation into one housing. Treatment and flow ofblood within the apparatuses is reflected in FIGS. 2-5. Various aspectsof the oxygenator apparatuses of FIGS. 2-5 are similar to those of theoxygenator apparatus 100 described above. In general terms, a blood flowpath (indicated by arrows “B”) is established from the blood inlet tothe blood outlet of the oxygenator apparatuses, including throughcross-sections of first, or oxygenating, zones and second, or GMEremoval zones as well as through and/or around other various componentsincluding in the oxygenator apparatuses. As discussed further below, insome embodiments, the gas exchange elements (or fibers) of theoxygenating membrane assembly can be wound directly on a core, a heatexchanger, or other centrally disposed body suitable for attachment andwinding of the gas exchange elements.

In one example embodiment illustrated in FIG. 2A, a portion of theoxygenator apparatus 200 (e.g., an upper end cap shown in FIG. 5 anddescribed below) and the central portion combine to form a de-aeringregion or bubble trap 250. A blood inlet (not shown) is arrangedrelative to the de-aering region 250 so as to direct incoming bloodtangentially into the de-aering region 250. A blood outlet (not shown)is positioned downstream of a heat exchanger 240 and the oxygenatingmembrane assembly 214. A blood flow path, indicated with arrows “B”, isdefined from the blood inlet to the blood outlet, with gross airremoval, indicated by arrows “GA” occurring within the de-aering region250, and prior to interaction of the blood with the heat exchanger 240or the oxygenating and GME removing membrane assembly 214.

The embodiment illustrated in the cross-sectionals views of FIGS. 2A and2B includes the heat exchanger 240 integrated within an oxygenatorapparatus 200. The heat exchanger 240 can be disposed in a zoneconcentrically about the central axis “C” and, in some embodiments, acentral displacement core 236 disposed along the central axis “C”. Themembrane assembly 214 can be disposed concentrically about the heatexchanger 240. The heat exchanger 240 is generally made of a metal orplastic that is able to transfer heat effectively to blood coming intocontact with the metal or plastic. With extracorporeal blood circuitapplications, the heat exchanger 240 is normally formed by a series orbundle of capillary tubes. The oxygenating membrane assembly 214 can bedisposed directly over the capillary tubes of the heat exchanger 240.

A suitable heat transfer fluid, such as water, is pumped through thecapillary tubes of the heat exchanger 240, separate from the blood butin heat transfer relationship therewith. The heat transfer fluid flowpath, indicated by arrows “H”, is either heated or cooled externally ofthe oxygenator apparatus 200 and the heat exchanger 240 disposed within.The heat exchanger 240 functions to control or adjust a temperature ofthe blood in a desired direction as the blood flows around and past thehollow fibers of the heat exchanger 240. Typically, the patient's bloodflow path, indicated with arrows “B” extends through the heat exchanger240 after flowing through the de-aering region 250, prior to interfacingwith the first oxygenation zone 222 of the membrane assembly 214.

The heat exchanger 240 is fluidly open to the membrane assembly 214concentrically disposed around the heat exchanger 240. After contactingthe heat exchanger 240, the blood then flows radially outward to thefirst zone 222 of the membrane assembly 214. The first zone 222 isfluidly open to the second zone 224. The first zone can be configured tobe fluidly coupled to an oxygen source to supply oxygen to an interiorof the plurality of gas exchange elements. A negative pressure sourcecan be fluidly coupled to the plurality of gas exchange elements to pullgaseous micro emboli (GME) from the plurality of gas exchange elementsin the second zone. The negative pressure source can be used to applysuction to remove gaseous micro emboli from blood circulated through theapparatus. In some embodiments, the first zone 222 has an enlargedvolume as compared to that of the second zone 224. The blood outlet isformed by or assembled to the central portion and is fluidly open to thegaseous emboli removal zone. In this regard, in some embodiments, theblood outlet extends radially relative to the central axis “C”.

As indicated by arrows “B” in FIGS. 2A and 2B, the blood flow pathenters the oxygenator apparatus tangentially, then circularly andlongitudinally along the core 236, continuing radially through each ofthe heat exchanger 240 zone, the first (oxygenation) zone 222, and thesecond (GME removal) zone 224. As illustrated in FIG. 2A, separate gasflow pathways are defined by the separate zones formed by the fibers ofthe heat exchanger 240 with a heat transfer pathway (indicated witharrows “H”), the first plurality of gas exchange elements 220 a in thefirst zone 222 with an oxygenation pathway (indicated with arrows “0”),and the second plurality of gas exchange elements 220 b in the secondzone 224 with negative pressure facilitating GME removal (indicated witharrows “G”). The apparatus 200 can thus perform gross air removal,temperature control, oxygenation, and gaseous micro emboli (GME) removalof the patient's blood (as part of an extracorporeal blood circuit) withefficiency and effectiveness in each component or zone.

FIG. 3 illustrates an example embodiment of an oxygenator apparatus 300including a de-aering region or bubble trap 350 and a membrane assembly314 including first and second plurality of gas exchange elements 320 a,320 b. In one embodiment, blood is directed from an inlet (not shown)tangentially into the de-aering region 350. Gross air removal from theblood, indicated by arrows “GA” occurs within the de-aering region 350prior to interaction of the blood with the oxygenating and GME removingmembrane assembly 314. A blood flow path, indicated with arrows “B”,continues from the de-aering region 350 and longitudinally along thecentral axis “C” to flow radially through the first zone 322 and thenthe second zone 324. As described above with respect to apparatuses 100and 200, separate gas flow pathways are defined by the separate zonesformed by the fibers of the first plurality of gas exchange elements 320a with an oxygenation pathway (indicated with arrows “0”), and thesecond plurality of gas exchange elements 320 b with negative pressurefacilitating GME removal (indicated with arrows “G”).

As illustrated in the example embodiment of FIG. 4, a fluid collectiondevice 460 can be disposed along a vacuum line 462, between an outletport of the oxygenator apparatus 400 and a negative pressure source 470.The fluid collection device 460 can be included with any of theapparatuses 100, 200, or 300. The fluid collection device 460 can beused to trap fluids 461, such as blood plasma liquids, that may bepulled from the blood through the fiber walls of the second plurality ofgas exchange elements 420 b in a second zone of a membrane assembly 414by the negative pressure source 470. The fluid collection device 460 canbe a disposable container removably connected to the vacuum line. Thevacuum line 462 can include an air gap at the fluid collection device460, essentially separating the vacuum line 462 into first and secondportions 462 a, 462 b to allow fluids (e.g., plasma) to enter the fluidcollection device 460 and gases to be suctioned past the fluidcollection device 460 by the negative pressure source 470.

FIG. 5 illustrates an example cross-sectional view of an oxygenationassembly 500 including a housing 512. The housing 512 can includevarious components separately formed and subsequently assembled to oneanother, such as a first or upper end cap 513, a central portion orchamber 515, and a second or lower end cap 517. The end caps 513, 517are configured for assembly to opposing ends of the central portion 515.In other constructions, the central portion 515 is integrally formedwith one or both of the end caps 513, 517. The housing 512 can be madeof a transparent medical grade material, such as transparentpolycarbonate, so that a user is able to observe the flow of bloodthrough the apparatus 500.

The housing 512 includes a blood inlet 516, a blood outlet 518, and ablood flow path, indicated by arrows “B”, from the blood inlet 516 tothe blood outlet 518. In one embodiment, the blood inlet 516 is arrangedto direct incoming blood into the housing 512 at a first, or proximal,end and toward the central axis “C” of the housing 512. The blood inlet516 can be integrally formed by the first end cap 513. Alternatively,the blood inlet 516 can be separately formed, and subsequently assembledto, the first end cap 513. In one embodiment, the blood outlet 518 isdisposed radially outward from the blood inlet 516. In some embodiments,when a de-aering region 550 is included, the blood inlet 516 is fluidlyopen to a first chamber including the de-aering region 550. To this end,the blood inlet 516 is arranged such that the opening opens tangentiallyalong a horizontal plane (i.e., perpendicular to the central axis “C”)into the de-aering region 550. With this construction, the blood inlet516 directs incoming blood substantially tangentially into the de-aeringregion 550 to produce a rotational flow along a side wall, and inparticular a vortex flow. An air purge port 521 formed at or by the topwall being fluidly open to the de-aering region 550.

The central portion 515 of the housing 512 has a substantiallycylindrical shape, and when assembled to the first and second end caps513, 517, generally defines the chamber 515 with a central axis “C”extending longitudinally therethrough. In some embodiments, a volumedisplacing core 536 is disposed along the central axis “C” and a first(oxygenation) zone 522 and a second (gaseous micro emboli removal) zone524 of a oxygenating membrane assembly 514 can be disposedconcentrically around the core 536. In one embodiment, a heat exchanger540 is included between the core 536 and first zone 522 to effectuatetemperature control of the blood. A heat exchange medium flow path,indicated with arrows “H”, can be established from a heat exchangerinlet port 525, through the fibers of the heat exchanger 540, and to aheat exchanger outlet port 529. The blood outlet 518 is positioneddownstream of the heat exchanger 540 and the oxygenating membraneassembly 514. A first plurality of gas exchange elements 520 a in thefirst zone 522 can be fluidly connected to a supply of an oxygencontaining medium at an oxygen inlet port 523. Oxygen medium can beprovided to the blood flow through the interior lumens of the firstplurality of gas exchange elements 520 a, indicated by arrows “0”, andcarbon dioxide removed from the blood through the interior lumens of thefirst plurality of gas exchange elements 520 a to exit the apparatus500, such as to be vented to the atmosphere (not shown). The secondplurality of gaseous exchange elements 520 b in the second zone 524 arefluidly coupled to a negative pressure source at a suction, or negativepressure, outlet 527. The outlet 527 illustrated at the second end cap517 would be useful, for example, with embodiments including the oxygenflow “0” and the GME flow “G” are generally parallel flows in the samedirection, as shown (also see, e.g., FIG. 1A). Alternatively, thesuction outlet 527 may be disposed at the first end cap 513 (not shown),with embodiments including the oxygen flow “0” transferred from thefirst plurality of gas exchange elements 520 a to the second pluralityof gas exchange elements 520 b at the second end cap 517 (distal end)and the GME flow “G” through the second plurality of gas exchangeelements 520 b is in a generally opposite direction to the oxygen flow“0” (e.g., FIG. 1B).

The housing 512 can form or carry other ports in addition to thosedescribed above. The second end cap 517, or the distal end of thehousing 512, can include a divider 519 for fluidly separating, orisolating, a distal end of the plurality of gas exchange elements 520between the first (oxygenation) zone 522 and the second (gaseous microemboli removal) zone 524. In some embodiments, the plurality of gasexchange elements 520 can be fluidly separated at the between the first(oxygenation) zone 522 and the second (gaseous micro emboli removal)zone 524 at the first end cap 513, or the proximal end of the housing512, with a divider 519.The dividers 519 in the first and/or second endcaps 513, 517 provide separation between the first zone 522 and secondzone 524, with a suction outlet included at the second zone 524. Thesecond zone 524 is fluidly open to the blood outlet 518 and the suctionoutlet 527 to maximize GME removal from the blood. Dividers 519 can alsobe included at one or both of first and second end caps 513, 517 betweenthe heat exchanger 540 and the first zone 522. Dividers 519 can be ringshaped or other suitable shape.

FIG. 6 is a schematic illustration of an example extracorporeal circuit700 including an oxygenator apparatus 600 of the pending disclosure. Theoxygenator apparatus 600 is akin to any of the oxygenator apparatuses100, 200, 300, 400, 500. The circuit 700 generally draws blood of apatient 702 during cardiovascular surgery through venous line 704.Venous blood drawn from the patient 702 is discharged into a venousreservoir 706. Cardiotomy blood and surgical field debris are aspiratedby a suction device 708 and are pump by a pump 710 into a cardiotomyreservoir 712. Once defoamed and filtered, the cardiotomy blood is alsodischarged into the venous reservoir 706. Alternatively, the function ofthe cardiotomy reservoir 712 may be integrated into the venous reservoir706. In the venous reservoir 706, air entrapped in the venous bloodrises to the surface of the blood and is vented to the atmosphere.

A pump 714 draws blood from the venous reservoir 706 and pumps itthrough the apparatus 600. As described above, the blood may bede-aerated, temperature controlled, oxygenated, and GME filtered by theoxygenator apparatus 600, and then returned to the patient 702 via anarterial line 716. A suction line 720 can connect to the suction device,or negative pressure source, 708 to apply suction to and pull GME fromthe blood in the oxygenator apparatus 600 prior to the blood beingreturned to the patient 702 via the arterial line 716.

Although the present disclosure has been described with reference topreferred embodiments, workers skilled in the art will recognize thatchanges can be made in form and detail without departing from the spiritand scope of the present disclosure.

What is claimed is:
 1. A blood oxygenator comprising: a housing defining a volume within the housing, a plurality of zones dividing the volume, a blood inlet, a blood outlet, and a blood flow path through the plurality of zones from the blood inlet to the blood outlet; a membrane assembly disposed within the housing, the membrane assembly including a first plurality of gas exchange elements disposed in a first zone of the housing and a second plurality of gas exchange elements disposed in a second zone of the housing, one of the zones arranged around another zone, the first zone and the second zone being fluidly open to one another along a body of the plurality of gas exchange elements and fluidly separated from one another along a distal end of the housing, each of the plurality of gas exchange elements including an interior gas side and an exterior blood side; in which the first zone may be fluidly connected to one of oxygen and negative pressure within the interior gas side of the first plurality of gas exchange elements of the first zone and the second zone may be fluidly connected to another of oxygen and negative pressure applied to the interior side of the second plurality of gas exchange elements in the second zone, and in which the blood flow path is sequential through the first zone and second zones to add oxygen to the blood and remove carbon dioxide from the blood at one of the first and second plurality of gas exchange elements, and to separate gaseous micro emboli from the blood at another of the first and second plurality of gas exchange elements.
 2. The oxygenator of claim 1, in which the distal end of the housing includes a divider for fluidly separating the distal end of one of the plurality of gas exchange elements between different zones.
 3. The oxygenator of claim 2, in which the distal end of the housing includes an outlet port for venting one of the plurality of gas exchange elements to atmosphere.
 4. The oxygenator of claim 1, in which the housing has a central axis and each of the first and second plurality of gas exchange elements are disposed concentrically around the central axis.
 5. The oxygenator of claim 4, in which the first and second plurality of gas exchange elements are each disposed helically around the central axis.
 6. The oxygenator of claim 5, in which the plurality of gas exchange elements is disposed helically around the central axis in a first direction in a first zone and the plurality of filter elements is disposed helically in a second direction in the second zone.
 7. The oxygenator of claim 1, further comprising a heat exchanger within the housing.
 8. The oxygenator of claim 8, in which the membrane assembly is disposed around the heat exchanger.
 9. The oxygenator of claim 1, further comprising a volume displacing core within the housing, the core configured to receive blood from a patient through the blood inlet.
 10. The oxygenator of claim 9, in which the membrane assembly is disposed around the volume displacing core.
 11. The oxygenator of claim 1, further comprising a de-aering region to remove gross air from the blood along the blood flow path prior to flow through the first zone.
 12. A method of oxygenating blood and removing gaseous micro emboli from the blood, comprising: delivering the blood from a patient to an oxygenator, the oxygenator comprising: a housing defining a volume within the housing, a plurality of zones dividing the volume, a blood inlet, a blood outlet, and a blood flow path through the plurality of zones from the blood inlet to the blood outlet; a membrane assembly disposed within the housing, the membrane assembly including a first plurality of gas exchange elements disposed in a first zone of the housing and a second plurality of gas exchange elements disposed in a second zone of the housing, one of the zones arranged around another zone, the first zone and the second zone being fluidly open to one another along a body of the plurality of gas exchange elements and fluidly separated from one another along a distal end of the housing, each of the plurality of gas exchange elements including an interior gas side and an exterior blood side; fluidly coupling the interior lumens of the plurality of gas exchange elements in the first zone to one of an oxygenation source and a negative pressure source, and fluidly coupling the interior lumens of the plurality of gas exchange elements in the second zone to another of an oxygenation source and a negative pressure source; and directing blood from the blood inlet to the blood outlet along the blood flow path to add oxygen to the blood and remove carbon dioxide from the blood at one of the first and second plurality of gas exchange elements, and to separate gaseous micro emboli from the blood at another of the first and second plurality of gas exchange elements.
 13. The method of claim 12, in which separation of gaseous micro emboli from the blood in the second zone is subsequent to adding oxygen to the blood in the first zone.
 14. The method of claim 12, further comprising removing gross air from the blood along the blood flow path prior to one of the first and second zones.
 15. The method of claim 12, further comprising transferring heat to the blood within the oxygenator by a heat exchanger prior to oxygenating the blood.
 16. The method of claim 12, further comprising collecting liquids from the interior lumens of the plurality of gas exchange elements fluidly coupled to the negative pressure source.
 17. A system for treating blood in an extracorporeal circuit, the system comprising: an oxygenator, comprising a housing defining a volume within the housing, a plurality of zones dividing the volume, a blood inlet, a blood outlet, and a blood flow path from the blood inlet to the blood outlet; and a membrane assembly disposed within the housing, the membrane assembly including a first plurality of gas exchange elements disposed in a first zone of the housing and a second plurality of gas exchange elements disposed in a second zone of the housing, the second zone arranged around the first zone, the first zone and the second zone being fluidly open to one another along a body of the plurality of gas exchange elements and fluidly separated from one another along a distal end of the housing, each of the plurality of gas exchange elements including an interior gas side and an exterior blood side; an oxygen source fluidly coupled to the first plurality of gas exchange elements at the first zone to provide oxygen to interior lumens of the first plurality of gas exchange elements; and a negative pressure source fluidly coupled to the second plurality of gas exchange elements at the second zone, the negative pressure source to provide suction to interior lumens of the second plurality of gas exchange elements, in which the system adds oxygen to the blood and removes carbon dioxide from the blood at the first plurality of gas exchange elements, and separates gaseous micro emboli from the blood at the second plurality of gas exchange elements. 